This democracy hasn't destroyed the world because it wants to live itself and MAD guaranteed that nobody wins a nuclear war. When it could use nuclear weapons without fear of retaliation, it happily used them on Hiroshima and Nagasaki.
Now it has gotten closer towards obtaining capability to start and win a nuclear war.
2. Iran hasn't started a war in a hundred of years, the Iran-Iraq war was started by Iraq, in which Saddam, who was supported by the US at the time, has used chemical weapons. You are clearly misinformed by your free press and Iran's desire to possess a nuclear deterrent is more than understandable.
* Since the invention of the H-bomb, nuclear powers have had the ability to knock out all fixed silos in a first strike. You don't need accuracy with a 10MT bomb. As accuracy improves, warheads get smaller, but the MAD calculus doesn't change: You can't guarantee you'll take out all the submarine, mobile, and airborne weapons too. Accuracy doesn't change anything.
* The US is not a dictatorship and the president doesn't have the ability to unilaterally start nuclear war. Hell, he can't even assassinate a foreign head of state. While I'm not thrilled with this particular president, I am confident that the democratic institutions of the US make nuclear first strike impossible.
There are a couple problems with your view of Iran:
* Iran and Iraq have been fighting since they were named Persia and Mesopotamia. Long before the official start of the Iran-Iraq war, both were funding and encouraging insurgent groups in the other. Khomeini openly called for the overthrow of Saddam via Islamic revolution. It doesn't matter who attacked first.
* Iran spent more than half of the Iran-Iraq war on the offensive in Iraqi territory. When they had power, they pressed their advantage. Khomeini spoke openly about spreading Islamic revolution everywhere, which is probably why all the neighboring nations lined up behind Iraq. The US was a tiny bit player; all Iraq's hardware came from the Soviets and all the money came from neighboring Arab states like Saudi Arabia and Kuwait (the joke would be on them later, apparently).
* Khomeini himself didn't want peace, even after 10 years of war: "Happy are those who have departed through martyrdom. Happy are those who have lost their lives in this convoy of light. Unhappy am I that I still survive and have drunk the poisoned chalice..."
There's almost nothing positive you can say about Iran's dictators since the Islamic revolution (and probably long before). Theocracies with martyr complexes must not be allowed to have nuclear weapons.
Also read: https://en.wikipedia.org/wiki/Iran–Iraq_War
* Giving the overwhelming advantage of the US and NATO in conventional weapons, the US doesn't need to actually commit a first strike to reap benefits of this capability. Nowadays the US and Russia are afraid to engage in a conventional conflict for fear of it escalating into nuclear war that would destroy both countries. After achieving first-strike capability, the US will know that Russia will be afraid to escalate by using tactical nukes against American carriers and troops.
Ultimately, this will mean that the US will be able to do
towards Russian allies or Russian expedionary forces whatever it feels like.